The Transgenic Mouse Core is a centralized facility designed to provide the techniques required by the individual projects for producing and maintaining transgenic mice. This facility will efficiently handle exacting techniques, such as microinjection of one cell embryos and the characterization of transgenic mice. The core will perform the following services: i) The core will produce transgenic mice using DNA submitted by each of the project investigators; ii) Transgenic mice will be identified by polymerase chain reaction (PCR) amplification procedures; iii) Transgenic founders will be further characterized by Southern analysis to determine the number of integration sites and the copy number of integrated transgenes; iv) Appropriate mice will be bred to maintain stocks and specific matings will be performed to establish transgenic lines homozygous for the transgene, as needed; v) The Transgenic Mouse Core will also be responsible for maintaining and housing mice for aging studies; and vi) Transgenic lines will be maintained through embryo cryopreservation. As a long-range goal the Core will establish techniques for obtaining and culturing embryonic stem (ES) cells. These cells will be available to generate transgenic mice via homologous recombination.